The invention refers to gas-heated hot-water boilers for household central heating and more precisely concerns a gas-tight chamber for heat exchangers of the type having water tubes surrounding a central burner.
Typically, the combustion chamber encloses a forced-air burner from which the gases are emitted radially and pass through the cylindrical layer of water tubes with which the thermal exchanges take place. The tubes are sized and arranged so as to obtain a laminar flow of gases and large heat exchange surfaces with them. These tubes are housed in a gas-tight chamber consisting of a shell the upper part of which communicates with an exhaust pipe. The combustion products are thus collected by this shell, which forms an exterior envelope around the combustion chamber. This shell, made--like all combustion chamber enclosures--of rigid sheet metal, is subjected to vibrations due to the compression waves emitted when the burner is lit and maintained by its flame front. These waves are reflected on the rigid wall of the shell which, by a phenomenon of resonance, emit a continuous, high-intensity noise, which is not acceptable for continuous-operation devices.